Surfacing machine drum



June 18, 1946. VAVR|K SURFACING MACHINE DRUM Filed Jan. 20, 1945 201/15 I JII HJK Patented June 18, 1946 SURFACING MACHINE DRUM Louis Vavrik, Itossford, Ohio, assignor to The American Floor Surfacing Machine Company, Toledo, Ohio, a corporation of Ohio Application January 20, 1945, Serial No. 573,728

2 Claims.

This invention relates to surfacing or sanding machines of the drum type, and particularly to the drums thereof on which the abrasive sheets are mounted.

These drums are hollow, preferably to reduce the weight, and heretofore, so far as I am aware, have been sand cast in sand molds, thus necessitating end openings to permit removal of the sand core. In the use of these drums it-is necessary to have them accurately balanced as to weight to prevent vibration at the high speeds at which driven, and it is found that with the use of sand cast drums accurate distribution of weight about the axis is not only difficult and uncertain, but that the provision of the core removal openings in the end webs permits the accumulation of dust and dirt in the interior of the drum and this may be unevenly distributed so as to effect the delicate balance required. It is also found in the use of these sand cast drums that considerable work and time is required to obtain the proper balance in weight.

An important object of the invention is to construct a hollow drum of the character described in such manner that its weight may be accurately distributed about its axis and may have its ends closed to prevent accumulation of dust and dirt therein.

Another object of the invention is to construct a drum of this character in a manner to permit easy and rapid balancing of its weight about the axis of rotation to compensate for a variance in weight of the clamping means for the encircling abrasive sheet.

Another object of the invention is to make a drum of this character in a plurality of sections which are capable of being quickly and accurately assembled in predetermined relation to form a complete drum of balanced constructions- Another object is to so construct and assemble the multiple parts of the drum in such manner that the parts may be cast in duplicate form from a single mold, thus facilitating and saving expense in manufacture.

Other objects and advantages of the invention will be apparent from the following detailed description thereof, and from the accompanying drawing, in which- Figure 1 is a central longitudinal section of a drum embodying the invention; Fig. 2 is an end view thereof with the abrasive sheet and clamping means therefor removed; Fig. 3 is an inner end view of one section of the drum; Fig. 4 is an inner end perspective view of the other section of drum with an abrasive sheet clamped in usable position thereon, and Fig. 6 is a perspective view of one of the clamping members for the abrasive sheet.

Referring to the drawing, l designates a drum of the type used in surface abrading machines, and 2 (Fig. 5) a strip of abrasive material, such for instance as sandpaper, mounted closely around the drum circumference and secured thereto in any suitable manner to hold it taut and render it easily and quickly replaceable. For this purpose the opposite end portions of the strip are usually inserted together in lapping relation inwardly through a radial slot 3 provided lengthwise in the drum rim and between a pair of opposing clamping rolls 4, 4 mounted in sockets or recesses 5, 5 in the walls of the slot. These rolls have side flats 6, which when in register permit the inturned strip ends to be inserted therebetween. When the rolls are turned to move the flats out of register they have a gripping action on the strip ends and serve both to draw the strip tightly around the drum circumference and to hold it in such position. This means of holding the abrasive sheet is commonly used in connection with drums of this character and no claim for novelty is made therefor.

The drum I is composed of two duplicate sections or halves I and I", the inner ends of which join in a central transverse line indicated at 8 in Fig. 1. These sections are adapted to be interengaged at their abutting ends to facilitate accurate assembly and to prevent relative turning when assembled by the provision of alternate studs and sockets 9 and I 0, respectively, on the inner end of one coacting with corresponding mating studs and sockets on the other. 'In the present instance, the studs and sockets are each in sets of two with the members of the sets disposed in diametrically opposed relation so as to enable the duplicate sections to be placed end to end with the portions of the slot 3 in each section in longitudinal register and with the studs registering with respective sockets.

Each drum section has a closed web H at its outer end and this is provided with a central bearing sleeve l2 for receiving a carrying shaft and at one side thereof adjacent to the slot 3, with the clamp receiving recesses-5, 5. A reinforcing rib l3 preferably extends from the sleeve I2 to each stud 9 and socket in. Each section is also provided, in diametrically opposed relation to the slot 3, with a part l4 forming a socket l5 therein immediately within the rim portion of the drum; Fig. 5 is a reduced end view of the the section and parallel to its axis for receiving a counterweight means l6. This weight means, in the present instance, is in the form of a plug having a forced fit in the socket and cooperating with the part I4 in which inserted and with the corresponding parts of the companion section to counterbalance the diametrically opposed Dortions of the drum which include the clamping rolls 4 and the parts in which disposed.

By die casting the drum sections, they may be so accurately made and in such well balanced proportions that practically the only purpose of the weights I6 is to counteract the weight of the clamping rolls 4 and possibly the weight of the extra abrasive sheet material used in the clamping operation. The drums operate at high speeds, frequently as high as 4000 R. P. M., and it is thus apparent that accurate balancing is necessary to prevent objectionable vibration, and this balancing may be easily and quickly accomplished by merely inserting a plug l6 of the desired Weight for the purpose in one Or both of the sockets I5.

The drum sections are secured together in assembled relation by tie rods ll' of ball form disposed in diametric relation and extending through Openings is in the end webs H of the sections.

I wish it understood that my invention is not limited to any specific construction, arrangement or form of the parts, as it is capable of numerous modifications and changes without departing from the spirit of the claims.

Having thus described my invention, what I,

claim as new, and desire to secure by United States Letters Patent, is:

1. A drum of the class described, comprising two sections separable in a line transverse to the drum axis, said sections being hollow with their outer ends closed and their inner ends open and each having its cylindrical portion provided with a. longitudinally extending slot for receiving the turned-in end portions of a drum embracing sheet, means within the slotted portion of each section to clamp and tighten said turned-in sheet ends, means for holding the sections in assembled relation with the inner ends of their cylindrical portions in close abutment with the slots in register, an enlargement on the inner side of the cylindrical portion of each section at the opposite side of the drum axis to said slot, the enlargements of the two sections cooperating to form a socket parallel to the drum axis when the sections are assembled with the socket open only when the sections are separated, and a replaceable counterbalancing means in said socket.

2. An arrangement as called for in claim 1 wherein the drum sections are duplicates and have the inner edges of their cylindrical portions provided With interengaging parts that insure assembling of the sections with the slots and the sockets therein, respectively, in register.

LOUIS VAVRIK. 

